1. Field of Invention
The present invention relates to a separating method and device, and in particular, to a method and device for separating charged particles in a liquid sample.
2. Related Art
Blood plasma is an important biological specimen capable of providing physiological or clinical information for medical or inspection unit to quickly comprehend the condition of a subject. Otherwise, blood plasma is also advantageous for showing the physiological condition of specific time point.
To achieve the above-mentioned purpose, many kinds of blood tests have to be well conducted with the blood plasma separated from whole blood. For example, blood coagulation test and cell-mediated or non cell-mediated immune response test of blood. All these tests are based on excellent blood plasma separation. Hence, multiple researches and developments are conducted regarding to the above needs in purpose of providing a method with excellent and fast separation to separate blood plasma from whole blood.
However, the conventional blood plasma separation needs to be conducted in the laboratory with centrifugation method. The centrifugation method is to store the whole blood into a test tube with anticoagulant; then, to centrifugate with high speed to separate different substances with different specific density, further to separate the blood cell and the blood plasma. But, the centrifuge is bulky, and the pre-treatment of sample, the standby procedure and the cleanness of the centrifuge are time-consuming. In addition, the transportation of the sample from hospital to laboratory is also time-consuming, which is inconvenient for medical personnel who need to know the test result at very short time. The centrifuge in the hospital or laboratory utilize large amount of blood samples in one time; however, most tests only need a small amount of blood plasma sample to get the desired result. Excess samples may cause the problems of recycling or pollution. Moreover, professional stuffs for operating the centrifuge are needed to be trained in advance, thus raising the cost.
In recent years, the techniques of biomedical inspection apparatus advance significantly, especially in the aspect of chips design. These newly developed tools are in replace of the conventional inspection devices with bulky volume, providing better applicability and operability. Lately, the micro fluidic chips used to separate blood plasma includes electrophoresis technique, dielectrophoresis technique, filter or changing the geometry of the flow channel.
Although it is easier to operate the electrophoresis or dielectrophoresis techniques, the electrophoresis or dielectrophoresis techniques need to be done under high voltage. Otherwise, it is not easy to manufacture the microchannel and install the filter. The method of changing the geometry of microchannel has to apply a micro pump to drive the sample, which easily caused qualitative change of the sample. Furthermore, using the external force to drive the sample to flow in the channel, including the early artificial pressing syringe and the recent pump, may limit the miniaturization of the chip, further increasing the manufacturing cost and complexity.
Therefore, it is an important subject to provide an apparatus for separating the blood plasma from Whole blood efficiently without external force, further making the blood plasma separation process more instant and simpler.